Metal materials, during hot rolling or heat treatment, can form a layer of compact covering on the surfaces thereof, known as “scales”. The existing of the scales can affect further processes in the following way:
On the one hand, the surface cracks on the metal materials are difficult to find earlier, such that quality problems exist on the finished products; on the other hand, the scales are prone to pressing into the metal surfaces so as to cause quality problems thereon. Additionally, hard oxides on the surfaces can accelerate the wearing of rollers or drawing machines. Therefore, descaling the surfaces of the steel plate before it entering cold roller is one of the necessary procedures in a cold rolling production line.
Aiming at the effects of the surface scales on metal materials, manufacturing enterprises in China and other countries utilize chemical hydrometallurgy to eliminate the attached scales on the surfaces of the metal plate strip. For steel plates, highly acidic solutions, like sulfuric acid, hydrochloric acid and hydrofluoric acid, are typically used. However, the pickling process with chemical hydrometallurgy is exposed to a severely-polluted manufacturing environment, and has to perform cycle regenerative procedure for the mass residual acids produced during manufacturing, which, inevitably, generates corresponding emission of waste gas including large quantity of acidic and corrosive components like HCL, SO2, which leads to direct atmosphere pollution.
Based on the fact, to solve the aforementioned severe pollution problems caused by the chemical washing method, much researches are conducted and several techniques are developed to replace the chemical methods so as to eliminate scales on the metal surfaces. For instance, electrolytic descaling are used, which includes descaling methods like electrolytic grind descaling, electric discharging descaling, electron beam descaling, laser descaling, grind descaling, shot blasting descaling, alternating bend descaling, and the combination of the above different methods. Among these methods, the high-pressure jet-flow descaling technology is the fastest-growing one, and the industrialization course thereof is becoming more obvious.
However, this jet-flow method, due to its special descaling way, may cause following primary problems on the descaled surfaces:
1) because the jet flow eliminates the scales on the metal plates directly, the shaking of the plates, and the uneven scales and the like therewith, may directly result in the inconformity of descaling effects.
2) the descaling speed is low, and cannot be promoted revolutionarily.
Through looking up related patents, it is found that in metallurgy technology-developed countries, such as Japan, Germany, although many patents or patent applications for continuous jet-flow, grinding-brush descaling technologies are proposed, for instance, JP06108277A discloses a descaling process which combines spraying acids with brush rollers in continuous cold rolling line, JP55034688A discloses a descaling way which combines PV roll broking scales with mixed abrasive high-pressure jet-flow descaling, and JP57142710A, JP57068217A, JP59097711A in Japan and US20080108281(A1), US20080182486(A1), US20090227184(A1), etc. of Canadian TMV company discloses a series of steel plate surface descaling technologies after 2001; besides, patents or patent applications such as American US5388602, Japanese JP05092231A, JP09085329A and JP2002102915, the treatment effectiveness of metal plates after jet-flow descaling still needs to improve.